Process of recovering rosin from resinous wood



PROCESS OF RECOVERING ROSIN FROM RESINOUS WOOD George H. Cook, Jr., Brunswick, Ga., assignor to Hercules 2,757,169 Patented July 31, 1956 2 ried out without previous steaming of the wood. The solvent mixture removes from the pine wood, rosin and other resinous material, and, where the pine wood has not been previously steamed, turpentine and pine oil will Powder Company, Wilmington, DeL, a corporation of 5 also be extracted. The extract solution is then distilled Delaware to remove the solvents, and then turpentine and pine oil, No Drawing. Application July 9, 1953, if present, are also distilled off leaving a residue of pine Serial No.3-67,080 wood resin. The desirable constituents of pine wood 11 Claims. (Cl. 260-110) resin may be isolated by well known means. This invention relates to an extraction process and The mixed solvents of this invention represent a substantial im rovement over the solvents when used alone more particularly to an improved method for extractin extrapfigg resinous Wood For example when v e gii z g g ii g gggx be extracted with a stantially pure acetone or methyl ethyl ketone is used to extract resin, and the extract evaporated to remove keg' fgg g ggzi gisg 2 55 i zgfi fi 322 55: 15 tone, extracting and distilling apparatus constructed of of i Solvents heretofore utilized ho 3 been ordinary materials are excessively corroded rendering the process commercially unfeasible. Also, evaporation entirely safisfagtory from emclency standpoint and of the ketone extract of pine Wood resin results in fouliggg gf g z 2 2 23 ggi fgg ag g g g g g g zg i ing the distillation apparatus, an insoluble thermosetting extracted viih certain solvents foi exam le acetone precipitate forming on the Walls of the apparatus with p consequent reduction in distillation efliciency rendering and the drop liquor, as the resulting extract solution dismantling and cleaning mandatory Another disad g ig fg i g i sig ag 2' fg gg g 2 g fi i vantage of these ketones as a sole extracting solvent arises p p s from the fact that these ketones, in addition to removing the (gsngatlon appargtus thireby reducmgB efliclencfis 25 desirable resins from the resinous wood, also removes and ma y necessitating wor stoppage. ecause t e many undesirable materials such as Wood sugars, wood $552333? g gg gf fi gg ii l g 352 3 g acids, and aldehydes thereby rendering very diflicult the r ere en a production of products with desirable properties. In neeq for extractlon process .Whlch would permlt greater contrast, the mixed solvents of this invention do not corgsig i fgggg gg zgi g zg zig fi g i rode equipment, do not foul the distillation apparatus by prior artpmcesses e c nslcs o e precipitation and produce typical naval store products. The extracting power of the mixed solvents of this In aqcordance with thls mvemloil it has been fmind invention substantially exceeds that of aromatic hydrothat res in may be extracted from pine wood by treating carbon solvfinm For example, ungmund pine Wood the resmous wood with a mlxmre of a ketone. such as chips containing 23.5% water by weight extracted with acetone or methyl ethyl ketone and an aromatlc benzene at atmospheric pressure and 70 C. produced carbon solvent such as benzene. The proportion of a yield of 476 lbs. resin per ton of Wood on a dry Wood ketone tha g gzjgz g basis, Whereas under the same conditions comparable ture may range rom a out 0 y Weig t and a a chips extracted with an acetone-benzene mixture conketone ,concentratlon of f al?out 9 based on 40 taining 30% acetone by weight produced 531 lbs. of resin the weight of solvent IlllXtlllQ 18 particularly preferred per ton of dry Wood Using the same conditions of as producing the most outstanding advantages over prior perature and pressure with pine Wood 8 art processes. The extraction process of this invention containing 21% Water by Weight benzene produced}; prodllces an Increased yleld of resm m P wood yield of 580 lbs. per ton, whereas an acetone-benzene rangmg to 60lbs1per f Wood dependmg upon mixture containing 30% acetone produced a yield of the paftlcular f a employed: the 610 lbs. per ton. Comparable improvements over ben- FP of resm m the Wood the Percentage zene and toluene may be obtained using benzene-acetone clpmposition of the extracting mixture, and the na of and toluene-acetone mixtures, and benzene-methyl ethyl t ei aroriiatifilhygrticaiill n. f h ketone and toluene-methyl ethyl ketone mixtures having 11d ch -ryi g fu b1 ef rocelss g t 18 inventi n, P ketone concentrations ranging from 10-40% by weight, y p p y t e outhern 3 s leaflnne. and in no instance is the distilling apparatus fouled when in e orm o s ump woo root or tOP W 18 the extraction solution was evaporated followin retracted with a mixture of a ketone, such as acetone, and moval of any Water layer present an Q t hYdr0Car b011, for p benzene, until The table shows results of extracting pine wood with extraction is substantially completed The pine wood ketone-aroinati'c hydrocarbon mixtures compared with may be steamed before extraction with the ketone-aroresults obtained with benzene and toluene as sole exmatic hydrocarbon mixture or the extraction may be cartractants.

Table Temper e Analysis of Extract Wood Batch Particle Size Percent attire, Pressure, Solvent Mixture lbs. per Extraction H20 O. p.s.1.g tonwood Etficlency Acid Melting Percent N0. Point, Gasoline O. Insoluble 2 Ungroimd... 22.0 129 Benzene 436 9, 2" do 26.0 143 95 Toluene 403 3; it 2 22.0 95 10% Acetone-Benzene" 442 96.0 149 82 15 3 22.0 120 95 20% Acetone-Benzene 463 96.5 14s 82 15"? 24.0 95 20% Acetone-Toluene.- 456 94.9 151 83 13 7 25. 5 129 95 20% Methyl Ethyl Ketone 436 91.6 148 81 15: 2

81128118. 25.5 129 95 Benzene 420 88 2 152 79 12.2

1 Percentages refer to percent ketone in mixture based on mixture.

In carrying out the process of this invention any convenient conditions of temperature and pressure may be utilized. It is desirable, however, to use temperatures ranging from 100-175 C. using pressures of 50-200 p. s. i. g. For commercial practice it is preferred to use temperatures of 125-150 C. and pressures of 90-170 p. s. i. g. In general, the smaller the chip size of the resinous wood, the more moderate may be the extraction conditions without seriously reducing efficiencies.

Unlike some of the prior art processes, the practice of this invention does not require that the resinous wood have any particular moisture content or be milled to any impractically small size. The advantages of this invention may be obtained using wood containing from about moisture to upwards of 30% moisture and is particularly useful with wood containing from 15-25% moisture by weight. Notwithstanding this fact, however, it has been found that the spent wood produced as a by-product in the process of this invention has a lower moisture content than spent wood obtained by prior art processes and is more useful as fuel.

The mixed solvents of this invention may comprise a mixture of either acetone or methyl ethyl ketone or both with one or more aromatic hydrocarbon solvents having high solvency power for resinous material. Benzene, toluene, xylene and similar aromatic hydrocarbons or mixtures thereof with acetone or methyl ethyl ketone may be utilized, but benzene is particularly preferred, having been found to posses higher solvency power than related aromatic hydrocarbons.

The process of the invention can be utilized in either a batch or continuous operation and is suitable for countercurrent extraction techniques. In the latter type of operation, a quantity of wood is passed through a number of extraction stages and treated in each stage with, for example, an acetone-benzene portion. The extract solutions are maintained separate from one another. The extract solution from stage 1 is directly distilled, following removal of any water layer present, to recover solvents and resin. The extract solution from stage 2 is used to extract resins from. the fresh batch of wood chips entering stage 1 and the extract solution from each of the remaining stages is used as extractant in each of the preceding stages (based on the flow of wood chips through the operation). In the last stage of wood chip treatment, fresh mixed solvent is used as extractant. In this manner, maximum utilization of the extracting power of the solvent mixture is obtained in that the solvent mixture having the greatest extracting power contacts wood least rich in resin, and solvent mixture having the least extracting power (i. e., being richest in resin) contacts wood richest in resin. By operating in this manner equilibrium conditions may be maintained and the most eilicient use of solvent achieved.

What I claim and desire to protect by Letters Patent 1. In the process .of recovering rosin from resinous wood, the step comprising extracting the wood with a ketone-aromatic hydrocarbon solvent mixture containing from about 10% to about 40% ketone by weight, said ketone being selected from the group consisting of acetone, methyl ethyl ketone and mixtures thereof.

2. The process of claim 1 in which the ketone is acetone and the aromatic hydrocarbon is benzene.

3. The process of claim 1 in which the ketone-aromatic hydrocarbon solvent mixture contains from about 20- 30% ketone by weight.

4. The process of claim 3 wherein the aromatic hydrocarbon is benzene.

5. The process of claim 3 wherein the aromatic hydrocarbon is toluene.

6. The process of claim 3 wherein the ketone is ace tone.

7. The processof claim 6 wherein the aromatic hydrocarbon is benzene.

8. The process of claim 6 wherein the aromatic hydrocarbon is toluene.

9. The process of claim 3 wherein the ketone is methyl ethyl ketone.

10. The process of claim 9 wherein the aromatic hydrocarbon is toluene.

11. The process of claim 9 wherein the aromatic hydrocarbon is benzene.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Chastaignet: Chem. Abst., vol. 44, pp. 7528-29 (1950). 

1. IN THE PROCESS OF RECOVERING ROSIN FROM RESINOUS WOOD, THE STEP COMPRISING EXTRACTING THE WOOD WITH A KETONE-AROMATIC HYDROCARBON SOLVENT MIXTURE CONTAINING FROM ABOUT 10% TO ABOUT 40% KETONE BY WEIGHT, SAID KETONE BEING SELECTED FROM THE GROUP CONSISTING OF ACETONE, METHYL ETHYL KETONE AND MIXTURES THEREOF. 